Around 300 BC Seleucus I founded, on the current southeast coast of Turkey, the city of Seleucia Pieria. Located north of the mouth of the Orontes River and at the foot of the Amanus Mountains, he gave it the name of Pieria, because the place reminded him of the Macedonian region of the same name.
Seleucia Pieria soon became the seaport for the main city in the area, Antioquia del Orontes, and was a strategic enclave for the control of the Syrian region. For this reason, in 64 BC it was conquered by Pompey's troops, incorporating it into the Roman Empire.
The Vespasianus Titus Tunnel near the modern village of Çevlik, about 100 km west of Aleppo. Photo: f9project/Shutterstock.com
From the Amanus Mountains a stream flowed down to Seleucia Pieria, crossed the walls (whose perimeter was 12 kilometers), then ran through the center of the city and out to sea in the port area. The first years this was not a problem, but after a few decades the sediments carried by the river began to accumulate in the port, which made it necessary to dredge it regularly. The problem was aggravated during the thaw, when the river rose producing frequent floods.
So in the 1st century AD, when Vespasian was emperor, it was decided to channel the river, diverting it so that it surrounded the city instead of going through it. A dike or diversion dam and a channel that runs through two artificial tunnels were designed, reaching 875 meters in length, all excavated in the rock. The work could not be completed during Vespasian's life, and was continued by his son Titus, finishing it in the second century under Antoninus Pius.
The dam is made of masonry and was 16 meters high (today reduced to 4 meters by the accumulation of alluvial deposits), 5 meters wide and 175 meters in total length, and is located 44.30 meters above sea level. It is completed with a shallow embankment 126 meters long towards the upstream direction. This is followed by the approach channel, which is 55 meters long and converges at the entrance to the first section of the tunnel. It is rectangular in shape and carved out of limestone.
Photo: CCinar/Shutterstock.com
The first section of the tunnel is domed and at the entrance it measures 5.8 meters tall and 6.3 meters wide, and is 90 meters long. Three meters after the entrance, the tunnel’s cross-section changes to an almost rectangular shape—6.9 m wide and 6.5 m high at the outlet. A second channel, 64 meters long and 25 to 30 meters tall connects this first section of the tunnel with the second.
The second section of the tunnel is 31 meters long, wider and taller at the entrance (7.3 meters both) than at the exit (5.5 meters wide and 7 meters high). Both tunnels have a small spring water transport channel carved into the left wall, 0.4 meters wide and 0.3 meters high.
At the exit of the second section of the tunnel there is an aqueduct arch that crosses the discharge channel. This channel is 635 meters long. The hydraulic capacity of the system is calculated at about 70 cubic meters per second, while that of the tunnels is 150 cubic meters per second. The entire system was built solely using human power, to protect the city from flooding and prevent siltation of the port, while meeting the city's water needs during the summer.
Photo: ihsan Gercelman/Shutterstock.com
The men who built it were, according to Flavius Josephus, legionaries of Legion IIII Scythica and Legion XVI Flavia Firma, together with Jewish prisoners captured by Titus in the taking of Jerusalem in AD 70. The engineers who designed it belonged to the Legion X Fretensis.
According to UNESCO, it is one of the best examples of Roman engineering and one of the unique structures of the Roman world that offers solutions to urban problems. From the point of the architectural and engineering implementation, the tunnel is a peculiar structure being survived till today without any damage. This man-made structure also bears testimony to the Eastern Mediterranean world and Roman Diplomacy of the 1st and 2nd centuries AD.
Today you can visit the whole at the foot of the Nur mountains, next to the modern city of Çevlik, about 35 kilometers southwest of Antakya (ancient Antioch). An inscription carved into the rock at the entrance of the first tunnel section bears the names of Vespasian and Titus, and another located in the outlet channel, that of Antoninus.
Despite the river diversion system and all the efforts made over the decades, by the 5th century the port became muddy and the city declined, losing its commercial importance. In 540 AD it was conquered by the Sassanids, and definitively abandoned shortly after.
As for the tunnel and canal system, French archaeologist Victor Chapot, who visited it in the early 20th century, found that where the canal curves sharply to the west, it is broken. According to him, this gap at that point cannot be of natural origin and he believes it was made on purpose during the Arab invasion. It is through this opening that a good part, if not all, of the debris still escapes today.
References:
# Jona Lendering, Seleucia, Canal and Tunnel of Titus, Livius
# O. Erol P. A. Pirazzoli, Seleucia Pieria: an ancient harbour submitted to two successive uplifts, Nautical Archeological Society
# UNESCO
# Wikipedia
# The British Museum
This article was originally published in La Brújula Verde. It has been translated from Spanish and republished with permission.
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